The present invention relates to a method of moulding a settable material. More particularly, the present invention relates to a continuous process for moulding a settable material wherein interlinked moulds are displaced from a material feed and shrinkage in downstream moulds is compensated for by material flow from upstream moulds.
Various methods of moulding a settable material exist. For instance:                U.S. Pat. No. 1,049,644 “Mold forming and casting apparatus” describes a movable track that supports a continuous sand mould that defines a series of spaced mould cavities. The track conveys the sand mould along a decline past a ladle for filling the mould cavities with molten metal. A drawback of this system is that, adjacent mould cavities are not in fluid communication with each other. As such, metal shrinkage in a mould cavity cannot be compensated for by the flow of molten metal from an adjacent mould cavity.        U.S. Pat. No. 1,615,696 “Casting machine” describes a casting process wherein moulds connected to a continuous belt are passed by a cope for introducing molten metal into the moulds. A similar system is described in U.S. Pat. No. 3,099,867 “Casting machines”. A drawback of these systems is that, adjacent moulds are not in fluid communication with each other. As such, metal shrinkage in a mould cannot be compensated for by the flow of molten metal from an adjacent mould.        
U.S. Pat. No. 3,905,735 “Stack moulding apparatus” describes a process for stack moulding pressed articles. As with the patents referred to above, each moulded article in the stack is not in fluid communication with adjacent articles.
U.S. Pat. No. 2,742,682 “Continuous moulding apparatus” describes a movable track that supports a series of abutting sand moulds thereon. The track is inclined in the direction of mould travel. Each mould is in fluid communication with adjacent moulds via a channel. As the moulds are conveyed upwards, along the inclined track, a pouring basin/launder system pours molten metal into the channel, which molten metal travels along the channel to fill the mould located beneath the launder and lower moulds that have yet to reach the launder system. A similar system is described in U.S. Pat. No. 2,799,906 “Apparatus and method of filling ingot molds” and U.S. Pat. No. 2,910,745 “Moving mold casting apparatus”. A drawback of this system is that, after a mould has passed the launder system, shrinkage in a mould cannot be compensated for by the flow of molten metal from an adjacent mould.
Various other patents (for example GB895,426 “Improvements in and relating to shell moulds and cores” and U.S. Pat. No. 1,359,196 “Multiple mold casting apparatus”) describe vertical mould stacks, wherein each mould in the stack is in fluid communication with adjacent moulds, and wherein the mould stack is filled with molten metal from the top. A drawback of this casting method is that it is not continuous.
It is an object of the present invention to provide a method of moulding that addresses these drawbacks.